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Regex for first occurance of a word

Regex for first occurance of a word

A word is a unit of information that represents one or more letters i.e., from a-z or A-Z. In this article let's understand how we can create a regex for first word and how regex can be matched for a given first word.

Regex (short for regular expression) is a powerful tool used for searching and manipulating text. It is composed of a sequence of first words that define a search pattern. Regex can be used to find patterns in large amounts of text, validate user input, and manipulate strings. It is widely used in programming languages, text editors, and command line tools.

Structure of a word

The word should have the following criteria and structure-

  • one or more words with separated by space
  • the first word should be a valid word

Regex for checking the first occurance of a word in a sentence

Regular Expression for first occuring word design-


Test string examples for the above regex-

Input StringMatch Output
The design in the design system is greatdesign (the first one)
Make hay while the sun shinesNo Match

Note the i modifier in the regex takes care of the UPPERCASE letters.

Here is a detailed explanation of the above regex-


^ asserts position at start of a line
1st Capturing Group (.*?)
. matches any character (except for line terminators)
*? matches the previous token between zero and unlimited times, as few times as possible, expanding as needed (lazy)
\b assert position at a word boundary: (^\w|\w$|\W\w|\w\W)
default matches the characters default literally (case sensitive)
\b assert position at a word boundary: (^\w|\w$|\W\w|\w\W)
Global pattern flags
g modifier: global. All matches (don't return after first match)
m modifier: multi line. Causes ^ and $ to match the begin/end of each line (not only begin/end of string)

Hope this article was useful to check and match the first occurance of a word in a sentence.